Chick-fil-A has 1,775 U.S. stores, while KFC has 4,491. Despite a smaller footprint, Chick-fil-A's average sales are more than triple those of its larger competitor, Wong writes.

And Chick-fil-A achieves these results despite being closed on Sundays for religious reasons.

Wong illustrates a couple of reasons for Chick-fil-A's success.

1. Breakfast business. Chick-fil-A has a popular breakfast menu that helped elevate sales by 3.6% last year. This is crucial at a time when demand for breakfast is at an all-time high. While KFC also offers breakfast, sales sunk 2% at its locations.

2. Differentiated menu. Chick-fil-A has a menu that is different enough to set it apart from fast food competitors. Popular items include its signature chicken sandwich and waffle fries. However, Chick-fil-A also offers ice cream, milkshakes, and wraps. Long known as a carry-out dinner option, KFC has struggled to find its footing in the fast food space.